Changing Impellar on Volvo kamd 300

[john m]

I’ve just fitted new impellers on my 2 Volvo kamd300now I can’t seem to get them to prime , if I take the outlet hose off and pour water in it will pump it out then stop I changed the rubber oring on the front cover it must be something I’ve done as both engines are the same problem

 

[oldgit]

Correct impeller ?
Gaskets or "O" rings on facing plate doing their job ?

Are the "O" rings on the lids on the raw water filters properly seated ?
Have frequently seen a dab of white grease applied to "O" rings on the lid to help it give an even seal without it binding and allowing air to enter.

 

[gjgm]

I’ve just fitted new impellers on my 2 Volvo kamd300now I can’t seem to get them to prime , if I take the outlet hose off and pour water in it will pump it out then stop I changed the rubber oring on the front cover it must be something I’ve done as both engines are the same problem

I think they are supposed to self correct, but are the vanes facing the wrong way ? I would check that first if both engines have this issue.
Are you in the water? You could try putting it into Neutral and giving the engines a blip if is an airlock.

 

[john m]

I’ll try again next time I’m at the boat see if the white grease works

 

[Moodysailor]

If they won't prime, there is a problem with the sealing. It could be wear in the pump body, it could be slightly incorrect sized impeller or a problem with the face plate o-ring. Did you use a genuine or pattern impeller?
The vanes will be in the correct orientation the moment the engine turns over.
A note on white grease, VP supplies glycerin with their impeller kits for lubrication of the rubber seals, please try not to use a petroleum grease on these pumps or parts.

 

[david_bagshaw]

I’ve just fitted new impellers on my 2 Volvo kamd300now I can’t seem to get them to prime , if I take the outlet hose off and pour water in it will pump it out then stop I changed the rubber oring on the front cover it must be something I’ve done as both engines are the same problem

I have found non genuine jabsco impellers to be poor when put in pumps that are not almost new. the vanes are stiffer and dont seem to seal as well as the real item. turning the front plate , if possible helps, though I suspect if you have o rings that will not work.

look for wear groves on the back wall, in some of the jabsco variety there is a service kit for this item.

doesnt matter where the vanes were put as they flip over during the first start. Just imagine the problems if this was so , what would happen when the engine bounces back on shut down.

 

[vyv_cox]

doesnt matter where the vanes were put as they flip over during the first start. Just imagine the problems if this was so , what would happen when the engine bounces back on shut down.

I made a video to demonstrate this. Last item on this page
Water pumps
Sorry, it is far too long. Watch about 20 seconds of it!

 

[oldgit]

While not wishing to suggest that old and worn raw water pumps cannot be cause of grief.
Have yet to have problem with any half decent quality aftermarket impellors.
Any problems on first start have always been down to air leaks usually due my lack of attention installation.
Recently replaced an impellor on my generator, it then refused to run due to over heating.
Took the entire thing to bits twice in order to check impellor was (a) intact and (b) facing plate properly sealed...same result.
Checked raw water valve and pipe was clear......same again.
Spotted that somebody might have had problems with raw water filter as white grease had been smeared on "O" ring.
Surely Not.
Gave the lid a rather more than should be needed turn and Hey Presto.